The present invention broadly relates to a drafting arrangement of a spinning machine and, more specifically, pertains to a new and improved apparatus for stopping the feed of slubbing or other fiber material to a pair of inlet rolls of the drafting arrangement, the pair of inlet rolls comprising a driveable first roll and a second roll which is driveable by contact with the driveable first roll. The present invention also relates to a new and improved method for stopping slubbing or fiber-material feed.
Generally speaking, the new and improved construction of apparatus for stopping the feed of slubbing or other fiber material is of the type comprising means for forming a clamping location for the slubbing or other fiber material with the outer surface of the second roll, such means being at least substantially radially moveable relative to the second roll between a stand-by position and an operative position.
In spinning without opening or separation of the fiber material into individual fibers the fiber or fibrous material to be spun at an individual spinning station is normally supplied thereto by means of a drafting unit or arrangement, the latter comprising a plurality of roll or roller pairs. The fiber-material feed can be provided in the form of an untwisted strand, for instance a sliver, or a slightly twisted roving, for example, from the flyer. The term "slubbing" will hereinafter denote an elongate or rope-like or strand-like structure of fiber or fibrous material serving as feed for a spinning machine, irrespective of whether such feed is provided with a supporting twist or not.
When a yarn break or breakage occurs at a discrete spinning station the fiber-material feed thereat is advantageously interrupted upstream of the outlet or delivery roll or roller pair of the drafting unit or arrangement in order to reduce waste of fiber material and the risk that the slubbing, such as a roving, can wrap around an upper or lower delivery roll or roller in a fiber lap. For this purpose it is known to stop the inlet roll or roller pair of the drafting unit or arrangement in the event of a yarn break or breakage and to clamp the slubbing or other fiber material between the two inlet rolls or rollers. To resume spinning at this spinning station it is then only necessary to re-start or actuate the inlet roll or roller pair of the drafting unit or arrangement so that the previously clamped slubbing or other fiber material is again conveyed through the drafting unit or arrangement. However, for this purpose each inlet roll or roller pair of the entire drafting arrangement would have to be individually driven, in which event it would be impossible to use an uninterrupted or continuous drafting cylinder or roller such as in a ring spinning machine and relatively elaborate means would be required to disengage individual inlet roll or roller pairs from a common drive shaft.
It is also known in the event of a yarn break to move a clamping element into the converging space at the input side of the inlet roll or roller pair such that the slubbing or other fiber material is clamped between the clamping element and either one of the two inlet rolls or rollers. However, self-threading of the slubbing or other fiber material into the drafting unit or arrangement upon resumption of spinning is then no longer ensured and friction results between the clamping element and the drafting rolls or rollers as long as the yarn break has not been repaired, i.e. until clearance of the fiber-material feed stoppage.
It is known, for example, from German Published Pat. Application No. 2,952,533, published July 2, 1981 to raise the upper or pressing roll or roller away from the lower driven continuous inlet roll or cylinder in case of a yarn break or breakage and to clamp the slubbing or other fiber material at the raised and the now stationary upper or pressing roll or roller. The slubbing or other fiber material therefore remains threaded in the inlet roll or roller pair although the supply of slubbing or other fiber material to the respective spinning station has been interrupted. After clearance or elimination of the fiber-material feed stoppage and upon resumption of spinning, the raised upper or pressing roll or roller must be lowered to again engage with the lower driven continuous drafting roll or cylinder and the clamping action must be annuled. This known slubbing clamping device at the drafting unit of a spinning machine is relatively complicated and requires a corresponding constructional expenditure. Furthermore, the coordination of the various functions or operations is relatively difficult.
A further fiber-material stop mechanism is disclosed, for example, in British Pat. No. 1,438,276, published June 3, 1976. A pneumatic cylinder controls a ram. Extension of such ram causes it to trap the fibrous material at the pressing roller and then to move the latter away from the lower feed roller. The end of the ram is formed with a blade which is sufficiently narrow to engage flutes in the pressing roller and thus stop further rotation of the latter. This prior art construction is relatively complicated demanding a corresponding space requirement at the input side of the feed roller pair, the clamping location at the pressing roller being at a considerable distance from the nip line of the feed roller pair. Furthermore, the blade of the ram does not constitute a fiber-material guide element.
This basic principle of separating the inlet rolls or rollers which feed the fiber or fibrous material to the drafting arrangement or unit or, in other words, actuating a stop element in the event of a yarn break or breakage to move into the nip or press zone of the inlet roll or roller pair and to disengage them from one another, is also disclosed in the following publications of prior art:
1) German Pat. No. 3,100,049, published Aug. 5, 1982; German Pat. No. 3,145,798, published June 1, 1983 (Patent of Addition to aforesaid German Pat. No. 3,100,049); German Pat. No. 3,218,660, published Aug. 25, 1983 (Patent of Addition to aforesaid Pat. No. 3,100,049), German Published Pat. Application No. 3,226,151, published Jan. 19, 1984 (aforesaid Patent of Addition No. 3,145,798 is cited as prior art in this disclosure); and German Pat. No. 3,532,541, published Mar. 19, 1987, (aforesaid Patent of Addition No. 3,145,798 is cited as prior art in this disclosure):
A wedge-type element in the form of a shell or ring segment is rotatable at the lower inlet roll or roller. In the event of a yarn break, such shell or ring segment is rotated and moves with its front edge between the fiber material and the lower inlet roll or roller, thus clamping the fiber material and raising the upper inlet roll or roller. In another embodiment of the moveable stop element, the wedge-type element is a wedge-formed part which, in case of yarn breakage, is driven beneath the fiber stream or material and parallel thereto into the nip or press line of the inlet roll or roller pair. In this manner, the wedge-formed part clamps the sliver or roving against the upper roll or roller and raises the latter to be disengaged from the lower inlet roll or continuous cylinder.
2) German Published Pat. Application No. 3,048,481, published July 22 1982; German Published Pat. Application No. 3,119,408, published Dec. 9, 1982 (Patent of Addition to aforesaid Pat. No. 3,048,481); and
German Published Pat. Application No. 3,606,609, published Sept. 3, 1987:
The lower inlet roll is partially encased by a clamp segment. When required because of yarn breakage, this clamp segment is rotated into its operative position and secures the sliver or roving at the upper inlet roll and raises the latter from the lower inlet roll.
3) German Published Pat. Application No. 3,318,925, published Nov. 29, 1984 and German Published Pat. Application No. 3,327,966, published Feb. 21, 1985:
A clamp member having an elastic wedge-shaped front blade is rotatably mounted at a pivot. In case of yarn breakage the clamp member with its front blade is pivoted in the direction of the nip line of the inlet roll pair and a sectionally reinforced clamp edge transversely arranged at the front blade traps the fibrous material against the upper or pressing roll or roller and moves the latter away from the lower inlet roll or drafting cylinder.
In all these cases the clamping and raising element performs a tangential or grazing movement with respect to the fiber or fibrous material as well as to the upper inlet roll or roller, and this tangential movement applies both to the clamping/raising operation as well as to the releasing/lowering operation. Under normal circumstances, the clamping or stop element is driven between the two inlet rolls or rollers as far as the normal nip line of the inlet roll or roller pair.
Despite these and other suggestions for an apparatus for stopping fiber-material feed and despite the obvious advantages which would be provided by such an apparatus, no existing or prior art construction as yet has proven to be a substantially optimized solution.